• Proceedings of the KIEE Conference
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• 2002.06a
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• pp.187-190
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• 2002

In contrast to conventional electromagnetic motor, USM(Ultrasonic Motor), as piezoelectric ceramic applying ultrasonic mechanical vibration and as frictional-movement type motor, get rotational torque by elastic friction between stator and rotator, The USM, which is small motor without iron cores and coil as a simple structure, has little load weight, has character of high torque at low speed, and can apply a direct drive type without deceleration gear as low speed type. A response of USM from control input is satisfactory, and also generates much torque in low speed driving, and holding torque is much without supplying power. In this study, I designed and made Ultrasonic motor-digital multi controller(USM- DMC) using FPGA chip, A54SX72A made in Actel Corporation. By the minute, USM-DMC can control frequency, duty ratio, and phase difference of USM by llbit digital input from Pc. Therefore, when we use this controller, we can apply to typical parameter, frequency, phase difference, and voltage parameter, to control as well as we can do mixing control like phase-frequency, phase-voltage, frequency-voltage, frequency-phase-voltage, What is more, the strongest point is that it can trace frequency based on optimized frequency because we can input optimized resonant frequency while in motoring.

• Journal of The Korean Astronomical Society
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• v.56 no.2
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• pp.169-185
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• 2023

The GMT-Consortium Large Earth Finder (G-CLEF) is the first instrument for the Giant Magellan Telescope (GMT). G-CLEF is a fiber feed, optical band echelle spectrograph that is capable of extremely precise radial velocity measurement. G-CLEF Flexure Control Camera (FCC) is included as a part in G-CLEF Front End Assembly (GCFEA), which monitors the field images focused on a fiber mirror to control the flexure and the focus errors within GCFEA. FCC consists of an optical bench on which five optical components are installed. The order of the optical train is: a collimator, neutral density filters, a focus analyzer, a reimager and a detector (Andor iKon-L 936 CCD camera). The collimator consists of a triplet lens and receives the beam reflected by a fiber mirror. The neutral density filters make it possible a broad range star brightness as a target or a guide. The focus analyzer is used to measure a focus offset. The reimager focuses the beam from the collimator onto the CCD detector focal plane. The detector module includes a linear translator and a field de-rotator. We performed thermoelastic stress analysis for lenses and their mounts to confirm the physical safety of the lens materials. We also conducted the global structure analysis for various gravitational orientations to verify the image stability requirement during the operation of the telescope and the instrument. In this article, we present the opto-mechanical detailed design of G-CLEF FCC and describe the consequence of the numerical finite element analyses for the design.

• Journal of the Korean Arthroscopy Society
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• v.13 no.2
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• pp.179-182
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• 2009

Purpose: Point fixation at the margin of the glenoid is a limitation of conventional arthroscopic stabilization using suture anchors, and does not afford sufficient footprint healing, especially in glenoid bone deficiency. So, we introduce an arthroscopic suture bridge transosseous-equivalent technique for bony Bankart lesions to avoid the technical disadvantage of point contact with anchor fixation and to improve mechanical stability through cross compression of the labrum. Surgical approach: The technique was adapted from the transosseous-equivalent rotator cuff repair technique using suture bridges, which improved the pressurized contact area and mean pressure between the tendon and footprint. After preparation of the glenoid bed by removal, reshaping, or mobilization of the bony lesion, two anchors (3.0 mm Biofastak, $Arthrex^{(R)}$, Naples, FL) were inserted into the superior and inferior portion of the bony Bankart lesion. Using a suture hook, medial mattress sutures were applied around the capsulolabral portion of the IGHL complex to obtain sufficient depth of glenoid coverage. A 3.5 mm pushloc anchor ($Arthrex^{(R)}$, Naples, FL) hole was made in the articular edge of the anterior glenoid rim. distal, suture bridge was applied, and proximal was inserted to mobilize the labrum in the proximal direction. This avoided the technical disadvantage of point contact with anchor fixation and decreased the level of gap formation through cross-compression of the labrum.